Woah, pretty extensive read. One thing I noticed though, is the author seems to assume that blockchain.com wallets is the only one available for Bitcoin users:
therefore, if 3 million active Bitcoin users represent about 17% of all Bitcoin owners, then the total number of Bitcoin owners around the world is only around 17.6 million.
He is quite right for that number of active users and I think it might be even an overstatement.
Let's say 3 million "active" bitcoin users, so that's at least 2 tx a month to qualify as active, it makes 6 million tx a month, 200k a day, that was the median for the last year.
And we have about 25 million addresses with a balance, since my two wallets have about 17 of those, it does fit.